1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef __X86_KERNEL_FPU_XSTATE_H 3 #define __X86_KERNEL_FPU_XSTATE_H 4 5 #include <asm/cpufeature.h> 6 #include <asm/fpu/xstate.h> 7 #include <asm/fpu/xcr.h> 8 9 #ifdef CONFIG_X86_64 10 DECLARE_PER_CPU(u64, xfd_state); 11 #endif 12 13 static inline void xstate_init_xcomp_bv(struct xregs_state *xsave, u64 mask) 14 { 15 /* 16 * XRSTORS requires these bits set in xcomp_bv, or it will 17 * trigger #GP: 18 */ 19 if (cpu_feature_enabled(X86_FEATURE_XCOMPACTED)) 20 xsave->header.xcomp_bv = mask | XCOMP_BV_COMPACTED_FORMAT; 21 } 22 23 static inline u64 xstate_get_group_perm(bool guest) 24 { 25 struct fpu *fpu = ¤t->group_leader->thread.fpu; 26 struct fpu_state_perm *perm; 27 28 /* Pairs with WRITE_ONCE() in xstate_request_perm() */ 29 perm = guest ? &fpu->guest_perm : &fpu->perm; 30 return READ_ONCE(perm->__state_perm); 31 } 32 33 static inline u64 xstate_get_host_group_perm(void) 34 { 35 return xstate_get_group_perm(false); 36 } 37 38 enum xstate_copy_mode { 39 XSTATE_COPY_FP, 40 XSTATE_COPY_FX, 41 XSTATE_COPY_XSAVE, 42 }; 43 44 struct membuf; 45 extern void __copy_xstate_to_uabi_buf(struct membuf to, struct fpstate *fpstate, 46 u64 xfeatures, u32 pkru_val, 47 enum xstate_copy_mode copy_mode); 48 extern void copy_xstate_to_uabi_buf(struct membuf to, struct task_struct *tsk, 49 enum xstate_copy_mode mode); 50 extern int copy_uabi_from_kernel_to_xstate(struct fpstate *fpstate, const void *kbuf, u32 *pkru); 51 extern int copy_sigframe_from_user_to_xstate(struct task_struct *tsk, const void __user *ubuf); 52 53 54 extern void fpu__init_cpu_xstate(void); 55 extern void fpu__init_system_xstate(unsigned int legacy_size); 56 57 static inline u64 xfeatures_mask_supervisor(void) 58 { 59 return fpu_kernel_cfg.max_features & XFEATURE_MASK_SUPERVISOR_SUPPORTED; 60 } 61 62 static inline u64 xfeatures_mask_independent(void) 63 { 64 if (!cpu_feature_enabled(X86_FEATURE_ARCH_LBR)) 65 return XFEATURE_MASK_INDEPENDENT & ~XFEATURE_MASK_LBR; 66 67 return XFEATURE_MASK_INDEPENDENT; 68 } 69 70 /* XSAVE/XRSTOR wrapper functions */ 71 72 #ifdef CONFIG_X86_64 73 #define REX_PREFIX "0x48, " 74 #else 75 #define REX_PREFIX 76 #endif 77 78 /* These macros all use (%edi)/(%rdi) as the single memory argument. */ 79 #define XSAVE ".byte " REX_PREFIX "0x0f,0xae,0x27" 80 #define XSAVEOPT ".byte " REX_PREFIX "0x0f,0xae,0x37" 81 #define XSAVEC ".byte " REX_PREFIX "0x0f,0xc7,0x27" 82 #define XSAVES ".byte " REX_PREFIX "0x0f,0xc7,0x2f" 83 #define XRSTOR ".byte " REX_PREFIX "0x0f,0xae,0x2f" 84 #define XRSTORS ".byte " REX_PREFIX "0x0f,0xc7,0x1f" 85 86 /* 87 * After this @err contains 0 on success or the trap number when the 88 * operation raises an exception. 89 */ 90 #define XSTATE_OP(op, st, lmask, hmask, err) \ 91 asm volatile("1:" op "\n\t" \ 92 "xor %[err], %[err]\n" \ 93 "2:\n\t" \ 94 _ASM_EXTABLE_TYPE(1b, 2b, EX_TYPE_FAULT_MCE_SAFE) \ 95 : [err] "=a" (err) \ 96 : "D" (st), "m" (*st), "a" (lmask), "d" (hmask) \ 97 : "memory") 98 99 /* 100 * If XSAVES is enabled, it replaces XSAVEC because it supports supervisor 101 * states in addition to XSAVEC. 102 * 103 * Otherwise if XSAVEC is enabled, it replaces XSAVEOPT because it supports 104 * compacted storage format in addition to XSAVEOPT. 105 * 106 * Otherwise, if XSAVEOPT is enabled, XSAVEOPT replaces XSAVE because XSAVEOPT 107 * supports modified optimization which is not supported by XSAVE. 108 * 109 * We use XSAVE as a fallback. 110 * 111 * The 661 label is defined in the ALTERNATIVE* macros as the address of the 112 * original instruction which gets replaced. We need to use it here as the 113 * address of the instruction where we might get an exception at. 114 */ 115 #define XSTATE_XSAVE(st, lmask, hmask, err) \ 116 asm volatile(ALTERNATIVE_3(XSAVE, \ 117 XSAVEOPT, X86_FEATURE_XSAVEOPT, \ 118 XSAVEC, X86_FEATURE_XSAVEC, \ 119 XSAVES, X86_FEATURE_XSAVES) \ 120 "\n" \ 121 "xor %[err], %[err]\n" \ 122 "3:\n" \ 123 _ASM_EXTABLE_TYPE_REG(661b, 3b, EX_TYPE_EFAULT_REG, %[err]) \ 124 : [err] "=r" (err) \ 125 : "D" (st), "m" (*st), "a" (lmask), "d" (hmask) \ 126 : "memory") 127 128 /* 129 * Use XRSTORS to restore context if it is enabled. XRSTORS supports compact 130 * XSAVE area format. 131 */ 132 #define XSTATE_XRESTORE(st, lmask, hmask) \ 133 asm volatile(ALTERNATIVE(XRSTOR, \ 134 XRSTORS, X86_FEATURE_XSAVES) \ 135 "\n" \ 136 "3:\n" \ 137 _ASM_EXTABLE_TYPE(661b, 3b, EX_TYPE_FPU_RESTORE) \ 138 : \ 139 : "D" (st), "m" (*st), "a" (lmask), "d" (hmask) \ 140 : "memory") 141 142 #if defined(CONFIG_X86_64) && defined(CONFIG_X86_DEBUG_FPU) 143 extern void xfd_validate_state(struct fpstate *fpstate, u64 mask, bool rstor); 144 #else 145 static inline void xfd_validate_state(struct fpstate *fpstate, u64 mask, bool rstor) { } 146 #endif 147 148 #ifdef CONFIG_X86_64 149 static inline void xfd_set_state(u64 xfd) 150 { 151 wrmsrl(MSR_IA32_XFD, xfd); 152 __this_cpu_write(xfd_state, xfd); 153 } 154 155 static inline void xfd_update_state(struct fpstate *fpstate) 156 { 157 if (fpu_state_size_dynamic()) { 158 u64 xfd = fpstate->xfd; 159 160 if (__this_cpu_read(xfd_state) != xfd) 161 xfd_set_state(xfd); 162 } 163 } 164 165 extern int __xfd_enable_feature(u64 which, struct fpu_guest *guest_fpu); 166 #else 167 static inline void xfd_set_state(u64 xfd) { } 168 169 static inline void xfd_update_state(struct fpstate *fpstate) { } 170 171 static inline int __xfd_enable_feature(u64 which, struct fpu_guest *guest_fpu) { 172 return -EPERM; 173 } 174 #endif 175 176 /* 177 * Save processor xstate to xsave area. 178 * 179 * Uses either XSAVE or XSAVEOPT or XSAVES depending on the CPU features 180 * and command line options. The choice is permanent until the next reboot. 181 */ 182 static inline void os_xsave(struct fpstate *fpstate) 183 { 184 u64 mask = fpstate->xfeatures; 185 u32 lmask = mask; 186 u32 hmask = mask >> 32; 187 int err; 188 189 WARN_ON_FPU(!alternatives_patched); 190 xfd_validate_state(fpstate, mask, false); 191 192 XSTATE_XSAVE(&fpstate->regs.xsave, lmask, hmask, err); 193 194 /* We should never fault when copying to a kernel buffer: */ 195 WARN_ON_FPU(err); 196 } 197 198 /* 199 * Restore processor xstate from xsave area. 200 * 201 * Uses XRSTORS when XSAVES is used, XRSTOR otherwise. 202 */ 203 static inline void os_xrstor(struct fpstate *fpstate, u64 mask) 204 { 205 u32 lmask = mask; 206 u32 hmask = mask >> 32; 207 208 xfd_validate_state(fpstate, mask, true); 209 XSTATE_XRESTORE(&fpstate->regs.xsave, lmask, hmask); 210 } 211 212 /* Restore of supervisor state. Does not require XFD */ 213 static inline void os_xrstor_supervisor(struct fpstate *fpstate) 214 { 215 u64 mask = xfeatures_mask_supervisor(); 216 u32 lmask = mask; 217 u32 hmask = mask >> 32; 218 219 XSTATE_XRESTORE(&fpstate->regs.xsave, lmask, hmask); 220 } 221 222 /* 223 * XSAVE itself always writes all requested xfeatures. Removing features 224 * from the request bitmap reduces the features which are written. 225 * Generate a mask of features which must be written to a sigframe. The 226 * unset features can be optimized away and not written. 227 * 228 * This optimization is user-visible. Only use for states where 229 * uninitialized sigframe contents are tolerable, like dynamic features. 230 * 231 * Users of buffers produced with this optimization must check XSTATE_BV 232 * to determine which features have been optimized out. 233 */ 234 static inline u64 xfeatures_need_sigframe_write(void) 235 { 236 u64 xfeaures_to_write; 237 238 /* In-use features must be written: */ 239 xfeaures_to_write = xfeatures_in_use(); 240 241 /* Also write all non-optimizable sigframe features: */ 242 xfeaures_to_write |= XFEATURE_MASK_USER_SUPPORTED & 243 ~XFEATURE_MASK_SIGFRAME_INITOPT; 244 245 return xfeaures_to_write; 246 } 247 248 /* 249 * Save xstate to user space xsave area. 250 * 251 * We don't use modified optimization because xrstor/xrstors might track 252 * a different application. 253 * 254 * We don't use compacted format xsave area for backward compatibility for 255 * old applications which don't understand the compacted format of the 256 * xsave area. 257 * 258 * The caller has to zero buf::header before calling this because XSAVE* 259 * does not touch the reserved fields in the header. 260 */ 261 static inline int xsave_to_user_sigframe(struct xregs_state __user *buf) 262 { 263 /* 264 * Include the features which are not xsaved/rstored by the kernel 265 * internally, e.g. PKRU. That's user space ABI and also required 266 * to allow the signal handler to modify PKRU. 267 */ 268 struct fpstate *fpstate = current->thread.fpu.fpstate; 269 u64 mask = fpstate->user_xfeatures; 270 u32 lmask; 271 u32 hmask; 272 int err; 273 274 /* Optimize away writing unnecessary xfeatures: */ 275 if (fpu_state_size_dynamic()) 276 mask &= xfeatures_need_sigframe_write(); 277 278 lmask = mask; 279 hmask = mask >> 32; 280 xfd_validate_state(fpstate, mask, false); 281 282 stac(); 283 XSTATE_OP(XSAVE, buf, lmask, hmask, err); 284 clac(); 285 286 return err; 287 } 288 289 /* 290 * Restore xstate from user space xsave area. 291 */ 292 static inline int xrstor_from_user_sigframe(struct xregs_state __user *buf, u64 mask) 293 { 294 struct xregs_state *xstate = ((__force struct xregs_state *)buf); 295 u32 lmask = mask; 296 u32 hmask = mask >> 32; 297 int err; 298 299 xfd_validate_state(current->thread.fpu.fpstate, mask, true); 300 301 stac(); 302 XSTATE_OP(XRSTOR, xstate, lmask, hmask, err); 303 clac(); 304 305 return err; 306 } 307 308 /* 309 * Restore xstate from kernel space xsave area, return an error code instead of 310 * an exception. 311 */ 312 static inline int os_xrstor_safe(struct fpstate *fpstate, u64 mask) 313 { 314 struct xregs_state *xstate = &fpstate->regs.xsave; 315 u32 lmask = mask; 316 u32 hmask = mask >> 32; 317 int err; 318 319 /* Ensure that XFD is up to date */ 320 xfd_update_state(fpstate); 321 322 if (cpu_feature_enabled(X86_FEATURE_XSAVES)) 323 XSTATE_OP(XRSTORS, xstate, lmask, hmask, err); 324 else 325 XSTATE_OP(XRSTOR, xstate, lmask, hmask, err); 326 327 return err; 328 } 329 330 331 #endif 332